The Pendulum Clock (1673) - Page 8

⚠Significant bleed-through from the title page on the verso is visible, including mirrored text ("CHRISTIANI HUGENII", "HOROLOGIUM OSCILLATORIUM") and a large printer's emblem. A modern institutional library stamp is visible on the center-right edge.

This book is divided into five parts,

of which

The First contains the Description of the PENDULUM CLOCK.

original: "Horologii Oscillatorii". This refers to Huygens' invention of the first functional pendulum clock.

The Second deals with the Descent of heavy bodies, and their motion in a Cycloid.

A cycloid is the curve traced by a point on the rim of a circular wheel as it rolls along a straight line. Huygens discovered that a pendulum swinging in this specific curve is "isochronous," meaning it takes the same amount of time regardless of the width of the swing.

The Third concerns the Evolution and Dimension of curved lines.

This section introduces the mathematical theory of "evolutes" and "involutes," which Huygens developed to create the cycloidal cheeks that guided his pendulum.

The Fourth concerns the Center of Oscillation or Agitation.

Center of Oscillation: The point in a compound pendulum where all its mass could be concentrated without changing its period of swing.

The Fifth presents the construction of another Clock, in which the

motion of the pendulum is circular, and Theorems

on Centrifugal Force.

original: "Vi Centrifuga". This is one of the earliest formal treatments of the force that acts on a body moving in a circular path, directed away from the center.